[unreadable] [unreadable] Numerous pollutant compounds are continuously released into the environment during their production, use and disposal. The resulting mixtures contaminate the environment and can be a potential threat to human beings. Heavy metals are significant environmental pollutants because they tend to persist in the environment, tend to bioaccumulate and can result in adverse health effects when ingested or inhaled. These metal species can be measured in human tissue or fluids such as blood or urine, usually in central laboratories using complex methods such as high-performance liquid chromatography inductively coupled plasma mass spectroscopy. However, in view of the high labor and analytical costs and long time delays associated with centralized laboratory analyses, there is an immediate need for a portable and inexpensive system for on-site monitoring of exposure to heavy metals in living systems, especially humans, as a result of exposure through drinking water, environmental, and industrial sources. Field deployable monitoring systems for in-situ, on-site, personal human exposure assessment will allow realtime monitoring of exposure to trace toxic metals, and facilitate the use of bio-monitoring data by allowing the instrument to be taken to the sample rather than the traditional way of bringing the sample to the laboratory. [unreadable] [unreadable] The overall objective of this project is to develop a portable, self-contained, easy-to-use monitor for simultaneous on-site measurement of arsenic, cadmium, mercury and lead metals from one urine sample, in near real time, to assess personal exposure. The proposed sensor will combine the high sensitivity of a specialized electrochemical measurement technique with a unique microarray electrode material and configuration. During Phase I, we will investigate sensor design configurations, electrode material composition, and the preliminary operating conditions which will demonstrate the feasibility of the unique microchip sensor prototype for detection of arsenic and cadmium species. At the conclusion of the Phase I/II program, a compact, packaged prototype sensor instrument will have been developed, tested and utilized in pilot epidemiological field trials. [unreadable] [unreadable] [unreadable] [unreadable]